This invention relates to a simple and effective monitor or warning system particularly adapted for use with small heating systems, such as residential or mobile home systems. More particularly, it relates to a monitor and warning device which is effective to visually or otherwise indicate the malfunction of each of a number of monitored system components and will effectively act as an aid in servicing the furnace by indicating, through the sequence of indicating devices, the exact point at which the serviceman should make his initial inspection.
Complex combustion systems, such as boiler and burner controls for electric utilities and other industrial melting furnaces incorporate sophisticated monitoring systems for indicating the status of various parts of the system, such as temperature, water level, turbine speed, steam pressure, etc. In such installations, the large industrial furnace is usually equipped with a central control room having an operating panel in which visual lights, meters or audible warning devices are used to assist a highly trained operator in correctly running the installation and in servicing component malfunctions or operating abnormalities. The hardware for such systems is well developed and is disclosed, for example, in U.S. Pats. Nos. 2,807,318, 3,566,398 or 3,641,539.
Apart from these types of installations in which a very large number of components in complex operating systems are monitored by skilled operators whose prime function is to keep the system operating and to make necessary repairs, simple systems such as household or mobile home heating plants have heretofore not been commercially equipped with any such control or warning systems. Because of the price of sophisticated controls, it has been felt that a monitor system of the type described above would be uneconomical with a simple heating system. In addition, the average householder or trailer owner would not be trained to recognize a signalled malfunction and be able to detect the malfunctioning component. Thus in the past, when a component of a residential furnace malfunctions, the householder either, through lack of heat, noise in the furnace, or other obvious failure would be led to place a service call with a local repairman who is presumably trained to service such systems. The time taken by the serviceman to locate the trouble will depend entirely upon his individual level of training, ingenuity and familiarity with the specific equipment involved. as humidifying and possibly electrostatic air cleaning units, the need for a monitoring and indicating device has become real. Not only should the device be able to indicate to the householder that there is a malfunction, it should also be able to assist the householder or the local repairman to locate and identify the source of the malfunction. It is for this important purpose that the control system of this invention is designed as will be more fully set forth below.